The main goal of the proposed research is the determination of the structure and function of binding proteins from bacterial cells. Since binding proteins are essential components of two biologically important cellular processes - active transport and chemotaxis - the proposed research will contribute to some understanding of these processes at the molecular level. To accomplish this goal, we proposed to: (1) determine by X-ray crystallographic technique the three-dimensional structure of sugar and amino acid binding proteins, in the presence and absence of specific ligands, (2) determine the rate constant of binding reactions in solution of binding proteins by stopped flow technique, and (3) study the liganded state of binding proteins by spectroscopic technique. The three-dimensional structure of L-arabinose-binding protein that we have recently determined at 3.5 Angstrom units resolution will be extended to atomic resolution.